Human cells contain singular DAN repair pathways to excise critical lesions from DNA. In individuals with clinical syndromes predisposing to malignancy, the capacity to excise these lesions is impaired. This research proposal is designed to continue our investigations on: (1) the biochemical and molecular mechanisms through which normal human cells regulate excision repair genes during cell proliferation; and (2) whether aberrations in regulatory mechanisms of DNA repair may provide a molecular mechanism for the cellular sensitivities of individuals who may be cancer prone. In particular, in this research proposal, we plan to determine the translational regulation of DNA repair enzymes during cell proliferation and after carcinogen exposure and subsequent DNA repair. Further, we seek to determine the immunological relationships of human DNA repair enzymes. For these studies we have developed a series of monoclonal antibodies to human placental uracil DNA glycosylases. Normal human cells and cells from cancer prone individuals will be used in all studies. The objectives of this proposal are: 1. To examine the immunological relationships and amino acid sequence homologies of uracil DNA glycosylases isolated from normal human calls and cells from cancer prone individuals. These relationships will be examined by radioimmunoassay using our monoclonal antibodies. 2. To determine the translational regulation of uracil DNA glycosylases during cell proliferation of normal human cells and cells from cancer prone individuals. Using our monoclonal antibodies, glycosylase regulation will be examined by 2 dimensional gel electrophoresis of immunoreactive species as well as by in vitro translation analysis using isolated poly (A) containing mRNA. 3. To determine the translational regulation of uracil DNA glycosylases in quiescent and in proliferating human cells after DNA damage and subsequent DNA repair.